The invention relates to an injector cap for an ampoule support. In particular, the invention relates to the field of so-called injection xe2x80x9cpensxe2x80x9d, i.e., pen-like injectors or injection devices such as are used for hypodermally administrating medicines, for example for administering insulin for diabetics. The application claims the priority of German patent application No. 100 09 814, filed on Mar. 1, 2000 with the German Patent and Trademark Office.
Basically, injection pens comprise an ampoule support on which a cannula support comprising a cannula is arranged on a facing side. A cap is fastened over the cannula or needle, said cap in its basic state completely hiding the cannula or needle. From this position, the cap can be retracted in the direction of the ampoule support, wherein the cannula emerges from a hole formed on the front facing side of the cap. It is therefore possible to place the pen on the skin, press on it such that the cap slides backwards against a spring force, administer the injection and remove the pen again, wherein the spring force ensures that the cap is returned to its initial position and the needle is hidden again. In this way, a user can administer the injection without ever even seeing the needle, which is particularly advantageous when patients who have phobias or aversions to needles are reliant on such treatments. Moreover, the cap protects the cannula from contamination.
A xe2x80x9cpenxe2x80x9d is known from U.S. Pat. No. 5,609,577 in which the cap can only be retracted once a holding mechanism is twisted up against a spring force. A disadvantage of the pen disclosed in the ""577 patent and other conventional injectors is that the cannula can easily be exposed again after the injector has been used. This creates the danger that a cannula which is no longer sterile is used a second time and so causes inflection. Furthermore, such an exposed cannula can cause injury and transmit diseases, which in the age of Aids can be life-threatening.
It is therefore the object of the present invention to provide an injector cap which does not exhibit the above disadvantages. In particular, the intention is to simply but reliably prevent the possibility of the cannula of an injector provided with the cap being used or exposed again after having been used once.
This object is addressed in accordance with the present invention by providing an injector cap for an ampoule support, said cap comprising a sliding sleeve slidably mounted on said ampoule support, wherein the sliding sleeve is pressed by a pre-tensioning means into a first position in which it covers a cannula, and wherein the sliding sleeve can be slid against the pre-tensioning into a second position in which the cannula emerges from the front facing end of the sliding sleeve, wherein a blocking means is provided which non-detachably blocks the sliding sleeve against sliding further when it has been returned from the second position to the first position. The invention further relates to an injector comprising an ampoule support of an injector cap in accordance with the invention.
In one embodiment, the present invention comprises an injector cap comprising a sleeve and a lock, wherein the sleeve is mounted slidably on a portion of an injection device, e.g., on an ampoule support, is forced by a pre-tensioning means into a first position in which it covers a cannula carried by the injection device, and can be slid against the pre-tensioning means into a second position in which the cannula emerges from the end of the sleeve, and wherein the lock non-releaseably locks the sleeve against sliding when it has been returned from the second position to the first position.
An advantage of the injector cap in accordance with the invention is that an injector equipped with said cap cannot be used again once it has been used once. Furthermore, it is not possible to expose again a cannula which has already been used once, such that the danger of injury and thus also the danger of infection are practically completely removed.
In one embodiment, the blocking means comprises locking means, by means of which the sliding sleeve is locked relative to a fixed part of the ampoule support, once it has returned to the first position. In particular, the blocking means can comprise a locking ring which is slidably mounted in the sliding sleeve and locks in behind a locking protrusion of a cannula support fastened to the ampoule support, when the sliding sleeve is slid into the second position.
In an embodiment of the latter variant, the locking ring comprises locking clips arranged circumferentially and converging inwards, which lock in behind the locking protrusion.
There exists the possibility of additionally providing spacer clips which the sliding sleeve pushes against, once the sliding sleeve has returned to the first position, and preferably via elastic stays on the sliding sleeve.
In accordance with an embodiment of the latter variant, the sliding sleeve comprises a stopper for the spacer clips of the locking ring which, when the sliding sleeve is transferred from the first position to the second position, slides the locking ring over the cannula support until the locking clips lock in behind the locking protrusion of the cannula support.
The invention further relates to an injector comprising an ampoule support and an injector cap designed in accordance with one or more of the embodiments described above. In one embodiment in this respect, the injector cap or cannula support is attached to the ampoule support via a thread means. If these components are screwed on, there no longer exists the danger of the injector cap latching via the blocking mechanism even when it is attached to the ampoule support for the first time, thus preventing its use.